Setup advice, please; unstable braking

I set up cars using a race rather than a hotlap loadout, i.e. medium/hard tires and at least 12 laps-worth of fuel. My MO is to practice and practice, refining the setup as needed, until I am on the pace (in the top third for the car/track combo in RSR) and then I adjust the fuel and tires and go into hotlap mode where, with softs and little fuel I can generally gain a second on my previous PB in race trim.

This system usually works well and last night I started getting consistent 1.54s at Monza in the Lotus Evora GTC, which is a decent race lap. I expected to hit low 1.52s (a very competitive hotlap) after making the above adjustments but I completely flamed out. The car in hotlap trim was very squirrelly under hard braking, I just could not get it slowed down and transition as smoothly from hard braking to throttle input. My best time was an embarrassing 1.55:xx. I realise that the car is going faster with less fuel and that I might have to move my brake points back, but it's the behavior under heavy braking and apparently long braking distance that seem problematic to me and if I brake too early to counteract this, I will lose the time anyway. I'm running a good, fast setup (for race, anyway) with the rear wing at 4. ABS is on, no other assists.

Can anyone suggest an explanation for this behaviour, or an adjustment I might make to counteract it? I am no setup guru so everything is basically at default, including brake bias, but I have worked hard on gearing and how little downforce I can get away with. As I say, this produced good laps with medium tires and 30L of fuel but running it with softs and 10L is unstable under braking (unless I was just too tired to concentrate).

Anyway, all suggestions will be most welcome. I need to revise my hotlap time on RSR as I am capable of at least two whole seconds faster than that 1.55. Here is the table for the combo:

http://tinyurl.com/nz6uk4d

 

diff coast at 90% and braking bias towards forward should help

 

I'll have to check the default setup later for the specifics, but in the meantime try increasing the front brake bias a % or 2 and increase the coast side of the diff a little.

Edit: LOL @demonized, at the same time!

 

Thanks! Trying that now...

 

It's the suspension guys, not the brake balance...

 

So what do you recommend. iVG? When it comes to this stuff you know your shizzle.

 

more precise please^^
I cant brake with this car either ;D

 

It's the tires. The car is about 1.3 sec faster at Monza on medium slicks than on soft slicks. On mediums you can brake a lot more predictably, therefore later; the car is less unstable under heavy braking.

I've driven many, many laps in this combo so I am confident about my data. A good lap on softs for me was in the low 1.55s, a horrible time. On mediums, with the same setup, I was constantly doing low 1.54s, a hotlap of 1.54:029 putting me at 122/279 on RSR. I set a new PB of 1.53:66 but RSR didn't allow it; RSR is much stricter about kerb cutting in Ascari than the sim is, which allowed the lap. My speed on the long straight crossing the start line mid-lap on mediums was 152-153 mph vs 149 mph on softs because on mediums I could take Parabolica much faster.

I can get a low 1.53 with this setup, I think; if anyone wants to test my conclusions I'd be happy to post the set. I wonder if this is true to life for this car or an anomaly that the devs might take a look at...

 

1:52.002 here on softs and no, mediums are not faster. Maybe you're overheating the softs? Have you checked the temps ? Do you have the Ov1 tyre info app?
Also in RSR medium times are much slower than softs so I don't think there is an issue with the game.
Try increasing the pressure on all tyres and add some roll bars. On which corner exactly is your problem?

 

Hmm, well as usual I am baffled in the face of superior talent. I have OV1 and will check temps; would you mind sharing your method for doing this and adjusting for it? I did not have problems on corners per se, I just found the car very unstable under heavy braking at the end of the long straights. I will follow your advice, many thanks.

 

It's been a while since I drove the GTC but I think you just have to learn to deal with the unstable braking. I think turning off ABS helps but that also has its downsides...

This is the only setup I have saved, so it's probably what I used.

 

The lotus gtc is a jumpy, wobbly, unstable car over bumps and kerbs. There isn't a lot I've found to help with that. As others have suggested, move he brake bias forward a bit, increase the fast rebound on the dampers, move the front toe to more neutral.

 

Amazing, I just cannot get this car to go fast at Monza on softs. The difference is astonishing. I guess I made and tested the setup, i.e. gearing and downforce (very low, 4 rear wing) for mediums but I have never experienced this before, not even with the GX. I guess I have a decent race setup but if I want a good qualifying setup for soft tyres, I'd have to start fresh from the default. Here is my setup in case it is of any interest.

 

I'll contact you later today or tomorrow. I've recently lost my hard drive and all my saved setups with it but I can tell you, it's not the braking bias. You can easily check that by braking in a straight line on the main straight. Slam the brakes and watch the slip angles on the Ov1 (the little yellow lines below the tyres). Rear tyres barely reach 30-40% even under heavy braking. The problem occurs once you start applying steering angle. The rear inside tyre unloads and locks up. That, I think, is causing your confusion.
You can put the bias forward but that won't yield any lap time as it lengthens your braking distance for the added stability.
What you can do however is make the rear end lean less, therefore unload the inside tyre less and enable trail braking.

That, combined with some damper tweaking for increased stability over kerbs, should give you much better lap time than simply putting the brake bias forward. As I said, I'll contact you soon with a setup that would help you (hopefully) and make you a little bit faster and more consistent.
Hope this helps for the time being.
Cheers.

 

That's extremely kind of you, iVG, I'll owe you a beer. Because I've never encountered an anomaly like this before I've been wondering what I might have done differently in setting the Lotus up for mediums. The only thing I can think of is that when working on the gearing for Monza I cranked up the final drive as a higher setting seems to offer a finer degree of control over individual gear ratios.

 

Need more info on what the car is doing under brakes... is it in a straight line or when you are trying to trail brake into a corner or releasing brakes to turn?

You could start with decreasing negative camber, bring the toe closer to 0, increase tyre pressure as a start.

 

I found with the GTC if you have the front too low/soft it will hit the suspension travel limit under hard braking. When it hits one side before the other it causes the car to dive off to the side and it becomes very unstable on bumps/curbs presumably due to the same effect.

Haven't looked at your setup, but if you want it stable under braking, raise the front height and/or use stiffer front spring and/or stiffer front arb. More toe can also help.

This is a setup I made for NurbGP. It's stable under braking for me.

https://dl.dropboxusercontent.com/u/63816631/AC/setups/djm NurbGP r1.ini

In this car, as with the GT3 cars, you need to have tyre wear on for the softs to work. They have a layer of harder compound that you have to wear off on your out lap. If you have tyre wear off they'll be slower than mediums.

 

That's true. Do you have tyre wear on?

 

No! I hotlap with tire wear off! Will change this setting right away and will report back, thanks! 112 on RSR with a 1.53:7x on mediums, I'll never be as fast as you, iVG but maybe this will get me another second and explain why the running on softs has been so frustrating. Thanks for all your help, guys.

 

...now I feel stupid.